Náttúrufræðingurinn - 1989, Page 28

Kópavogur was censused 108 times and
Grafarvogur 107 times between 16 March
1980 and 22 May 1981. We observed 52
bird species, of which the 14 species of
shorebirds are dealt with here, other spe-
cies are treated in a separate paper (Gar-
darsson and Nielsen in press).
The Oystercatcher (Haematopus ostra-
legus) was observed throughout the year
(Fig. 3). In Kópavogur peak numbers oc-
curred on 31 March 1980 (236) and 9 April
1981 (95) and in Grafarvogur on 5 April
1980 (224) and 21 April 1981 (106). Oyster-
catchers present on the estuaries in winter
did not feed much out on the mudflats but
preferred gravel and boulder beaches.
The first Ringed Plovers (Charadrius
hiaticula) were seen on 11 April 1980 and
16 April 1981. In Kópavogur peak num-
bers occurred on 8 May 1980 (56) and 10
May 1981 (39) and in Grafarvogur on 7
May 1980 (31) and 5 May 1981 (24). (Fig.
4). In spring 1980 there was a second peak
in numbers, on 28 May in Grafarvogur
(57) and 2 June in Kópavogur (40). These
spring peaks seem to reflect two main
waves of Ringed Plover migration in Ice-
land. The first wave consists of Icelandic
breeders that disperse after a short stay on
the coast, and the second consists of high-
arctic passage migrants. Few Ringed Plov-
ers were observed in mid-June but num-
bers started climbing at the end of June
and reached a peak in late July, 21 July in
Grafarvogur (26) and 27 July in Kópavog-
ur (25). Numbers were lower in summer
than in spring. The last Ringed Plovers
were seen on 26 August in Kópavogur and
3 September in Grafarvogur.
The first Golden Plovers (Pluvialis apri-
caria) were seen on 5 April in both years.
Relatively few Golden Plovers visited the
tidal flats in spring and all had dispersed
before mid-May (Fig. 5). Golden Plovers
were much more numerous in autumn.
The first adults were observed on 23 July,
the first juveniles on 3 August. Numbers
built up to a peak of 1200 on 26 Septem-
ber in Grafarvogur and 890 on 7 October
in Kópavogur. The last observation was
on 15 November. About half the Golden
Plovers in late August were juveniles
(Table 2). Six Golden Plovers collected in
Grafarvogur in September 1980 had fed
partly on land (on Coleoptera and per-
haps Lumbricidae) and partly on Mya
arenaria, Littorina spp. and other inver-
tebrates on the tidal flat (Table 3).
The Turnstone (Arenaria interpres) was
much more numerous in Kópavogur than
Grafarvogur (Fig. 6). They foraged main-
ly on the rockier parts of the estuaries. No
turnstones were seen in the study areas in
mid-winter but birds, probably from the
local wintering population, started visiting
the estuaries in February and March.
Numbers changed much in April-May but
because of local wintering birds it is diffi-
cult to say when the first migrants arrived
from abroad. The Iast Turnstones in
spring were seen on 29 May. The first re-
turning adults in summer arrived on 10 Ju-
ly, followed by juveniles 17 days later.
The Black-tailed Godwit (Limosa limo-
sa) was much more abundant in Grafar-
vogur than Kópavogur (Fig. 7). The first
migrants were seen on 22 April 1980 and
14 April 1981. Numbers built up rapidly in
both years, with two well-marked peaks in
1980, on 30 April (123) and 8 May (150),
but in 1981 numbers were much more
even, peaking on 24 April (113). Single
peaks occurred in spring 1979 and 1982.
Spring migration was over on 13 May in
1980 and 15 May in 1981. Black-tailed
Godwits did not use the estuaries to any
extent in late summer. This agrees with
other observations in Iceland and suggests
that Godwits go directly from their inland
breeding grounds to Western Europe.
The Redshank (Tringa totanus) was
abundant in both areas (Fig. 8). Numbers
started to build up in mid-April but arrival
of the first migrants was obscured by the
presence of a local wintering population.
Peak numbers occurred between 28 April
and 1 May. Following this the birds dis-
persed before mid-May. Numbers in-
creased again in late May 1980 to a peak
at the end of the month, the same trend
was observed in 1981. Similar increases
have been observed in other areas in Ice-
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